The goal of this proposal is to study the metabolism and function of neutrophils. Neutrophils are equiped with potent killing systems against micro-organisms as well as neoplastic cells. We propose to study: 1) the mechanism of phorbol myristate acetate induced neutrophil autotoxicity. Our preliminary results indicate that in the presence of phorbol myristate acetate, neutrophils kill neoplastic cells as well as themselves. 2) The mechanism of the oxidation of methionine by myeloperoxidase mediated micro-bicidal system. 3) The oxidation and inactivation of N-formyl methionyl oligopeptide chemoattractants by human neutrophils and myeloperoxidase system. 4) The metabolism and function of neutrophils from patients with suspected neutrophil dysfunction.